Action Points

Children with juvenile idiopathic arthritis (JIA) who have involvement of the temporomandibular joint (TMJ) have high levels of disease activity and disability as well as impaired quality of life.

Note that the study suggestst that clinicians should pay special attention to TMJ involvement in children with JIA and cervical spine involvement, polyarticular course, and longer disease duration.

Children with juvenile idiopathic arthritis (JIA) who have involvement of the temporomandibular joint (TMJ) have high levels of disease activity and disability as well as impaired quality of life, a cross-sectional study showed.

Compared with JIA patients without clinical manifestations of TMJ involvement, affected children had higher scores on the Juvenile Arthritis Disease Activity Score (20.6 versus 9.2, OR 4.6, 95% CI 3.7-5.8), according to Paula Frid, DDS, of University Hospital North Norway in Tromsø, and colleagues.

In addition, on the Childhood Health Assessment Questionnaire Disability Index (CHAQ-DI), those with TMJ involvement were four times more likely to have a score above 0.6 (OR 4.1, 95% CI 3.2-5.2), the researchers reported in Arthritis Care & Research.

Arthritis of the TMJ has been estimated to be present in some 40% of children with JIA by MRI assessment. It can be difficult to detect clinically in very young children, however, because many are asymptomatic. The result can be severe disturbances in facial growth and pain that can persist into adulthood.

"The growth disturbances in childhood TMJ arthritis are different from arthritis in other joints because of the special anatomy of the TMJ, with fibrous cartilage and the intra-articular condylar growth pattern. Bilateral involvement may lead to micrognathia and dental malocclusion, and unilateral involvement may lead to facial asymmetry," Frid and colleagues explained.

Little has been known, however, about the effects of TMJ arthritis on disability and quality of life in children with JIA.

The researchers, therefore, analyzed data from two studies conducted by the Pediatric Rheumatology International Trials Organization that included 3,343 children -- 387 of whom had clinically apparent TMJ involvement as evidenced by pain or limitations of motion in the jaw. In 80%, the arthritis was bilateral, and in more than 95%, the JIA disease course was polyarticular.

More than two-thirds of the patients were girls, and mean age was 10. The mean disease duration was 5.1 years in those with TMJ arthritis and 3.2 years in those without.

Among the TMJ patients, the physician's global assessment was higher (4.2 versus 2.3). In addition, the number of painful joints was greater (seven versus one), as was the number of active joints (eight versus two) and the number of joints with limitation of motion (13 versus two). Cervical spine involvement was present in 61.8% of the TMJ group compared with 17.2% of the non-TMJ group, for an odds ratio of 7.8 (95% CI 6.2-9.8).

On the 15-domain Child Health Questionnaire that rates physical, emotional, and social health, almost all scores were lower in the TMJ group.

Finally, on a multivariate analysis that adjusted for various factors such as number of active joints, erythrocyte sedimentation rate, and rheumatoid factor positivity, these characteristics were associated with clinical TMJ arthritis:

Cervical joint involvement, OR 4.6 (95% CI 3.5-6.1);

Disease duration longer than 4.4 years, OR 2.8 (95% CI 2.1-3.8);

CHAQ-DI above 0.6, OR 1.6 (95% CI 1.2-2.3); and

Female sex, OR 1.5 (95% CI 1.1-2.1).

"Special attention should be paid to the TMJ in children with cervical spine involvement, polyarticular course, longer disease duration, physical disability, and female gender," the researchers advised.

The team noted that arthritis of the cervical spine in patients with TMJ involvement may relate to "the close proximity of the neck and masticatory muscles."

Improved tools for assessment could be helpful, the researchers continued: For example, on the CHAQ, eating difficulties are solicited by the question, "Is your child able to cut his/her own meat?" which may reflect fine motor difficulties of the hands, rather than actual problems with eating. A new tool, the Juvenile Arthritis Multidimensional Assessment Report may better detect masticatory problems by asking questions such as whether the child is able to bite into a sandwich or apple.